This work aimed to study the prevalence and radiologic anatomy of the middle rectal artery (MRA) using computed tomographic angiography (CTA) and digital subtraction angiography (DSA). The retrospective study (October 2010-February 2012) focused in 167 male patients with prostate enlargement (mean age 64.7 years, range 47-81 years) who underwent selective pelvic arterial embolization for the relief of lower urinary tract symptoms. All patients underwent CTA previously to DSA to evaluate the vascular anatomy of the pelvis and to plan the treatment. MRAs were identified and classified according to their origin, trajectory, termination and relationship with surrounding arteries. We found MRAs in 60 (35.9 %) patients (23.9 % of pelvic sides, n = 80) and of those, 20 (12 %) had bilateral MRAs; 24 MRAs (30 %) were independent of neighbouring arteries and 56 MRAs (70 %) had common origins with prostatic arteries (prostato-rectal trunk). The most frequent MRA origin was the internal pudendal artery (60 %, n = 48), followed by the inferior gluteal artery (21.3 %, n = 17) and common gluteal-pudendal trunk (16.2 %, n = 13). In 2 patients the MRA originated from the obturator artery (2.5 %). Anastomoses to the superior rectal and inferior mesenteric arteries were found in 87.5 % of cases (n = 70). We concluded that MRAs are anatomical variants present in less than half of male patients; have variable origins and frequently share common origins with prostatic arteries. Their correct identification is likely to contribute to improve interventional radiology procedures and prostatic or rectal surgeries.